It is well known that pyrethroid compounds can be used to control mosquitoes and insects, and have a high pesticidal activity. They have been widely used in the field of sanitary pests control due to their outstanding properties, such as high efficiency, low toxicity and residue, and good environmental compatibility. However, mosquitoes have obtained certain resistance against some traditional pyrethroid products (for example, allethrin)(Gao Xiwu et al, Chinese Journal of Vector Biology and Control, 2004, 15 (2), 105), the additive amount of pyrethroid in mosquito-repellent incense or aerosol required to achieve the same effect in controlling sanitary pests as before is increased. Therefore, not only production cost is increased but also the burden of environment is aggravated.
CN 101381306A discloses a series of novel fluoro-containing pyrethroid compounds formed by structural transformation of acid and/or alcohol moieties in traditional pyrethroids. Preliminary efficiency tests on these compounds show that these compounds have good pesticidal activity, quick knock-down and high fatality rate. On the other hand, with the growing demanding for environment protection, people pay more attention to pesticides with high biological activity. Pyrethroids usually have many optical isomers, and the biological activity of each isomer is quite different, so the study on preparation of highly active isomer is necessary. In respect to environmental protection, the use of highly active isomer can reduce the amount of pesticides without reducing pesticide effect, therefore reducing the toxicity toward non-targeted organisms and improving safety, lessening environmental pollution of pesticide residue. Based on such an idea, we made a deep investigation on 2,3,5,6-tetrafluoro-4-methoxymethylbenzyl-3-(3,3,3-trifluoro-1-propenyl)-2,2-dimeth ylcyclopropane carboxylate with a good activity, the cyclopropane moiety of the compound has two asymmetric carbon atoms and therefore isomers exist, and the carboxylic acid moiety of the compound contains a carbon-carbon double bond and therefore Z and E isomers exist. We have found through experiments that the compound with an absolute stereochemistry of cyclopropane-1 of R configuration has higher efficacy than the compound with S configuration; the compound with carbon-carbon double bond of carboxylic acid moiety of Z configuration has better efficacy than the compound with E configuration of compounds, which proved that the 2,3,5,6-tetrafluoro-4-methoxymethylbenzyl-1R-(Z)-3-(3,3,3-trifluoro-1-propenyl)-2,2-dimethylcyclopropanecarboxylate is a highly active isomer. Using this compound to control sanitary pests doesn't have cross resistance as compared to prior traditional pyrethroid products such as allethrin, and greatly reduces the dosage and the use-cost, and therefore lessens the burden on the environment due to its high basic activity.